1. Field of the Invention
The present invention relates to a circuit board layout in a flat-panel display apparatus.
2. Description of the Related Art
A conventional flat-panel display apparatus is described with reference to FIGS. 10 and 11. FIG. 10 is a front view of a conventional flat-panel display apparatus, and FIG. 11 is an exploded perspective view of the apparatus.
Referring to FIGS. 10 and 11, a display panel 1 is an LCD panel or the like that displays images. A front bezel 2 is an exterior component that is arranged on the front of the display panel 1. A back chassis 5 holds the back of the display panel 1. A driver board 8 is supported on a back chassis 5 and drives the display panel 1 upon receipt of a control signal from a circuit board 14. The circuit board 14 is supported on the back chassis 5 and controls power supply to the display panel 1 and the driver board 8 and the output of display signals. Exhaust fans 15 are supported on the back chassis 5 and forcefully exhaust internal air. A rear cover 16 covers the driver board 8, the circuit board 14, and the exhaust fans 15 on the back chassis 5.
Although not shown, multiple circuit boards 14 are arranged above and below on the back chassis 5. Each circuit board 14 has multiple electrical components mounted thereon on the back side of the display panel. The circuit boards 14 are fixed with screws inserted into bosses provided in the back chassis 5. The circuit boards 14, the driver board 8 and so on are electrically connected to one another through cables and connectors, not shown. The front bezel 2 has an opening in the center so that the display panel 1 is exposed to the front. The rear cover 16 has vent-holes 16a and 16b for heat radiation in its lower and upper portions. The exhaust fans 15 are mounted on the back chassis 5 in the vicinity of the upper vent-holes 16b. 
Japanese Patent Laid-Open No. 2002-341777 describes a configuration, different from the configuration shown in FIGS. 10 and 11, in which each circuit board is arranged so that the electrical components mounted thereon face away from the display panel; and multiple circuit boards are vertically arranged above and below at different intervals on the back side of the display panel. With this configuration, a circuit board arranged below and a circuit board arranged above can be cooled by producing two air flow layers that represent different spacings. Another configuration is also described, in which a radiator plate is attached to the inner face of a member that corresponds to the rear cover, and an elastic thermal-conductivity member is provided between electrical components.
With the above-described Japanese Patent Laid-Open No. 2002-341777, a further reduction in the dimension of the thickness of a display device is difficult because of different spacings between the component mounting surfaces of the upper and lower circuit boards and the back side of the display panel. If the above spacings are made the same, air flowing upward is heated by the heat generated by the electrical components mounted on the lower circuit board, which results in a reduction in the cooling effect of the upper circuit board. Besides, the upper circuit board is required to take some countermeasures such as mounting highly heat-resistant components that are capable of resisting the influence of the heat generated by the lower circuit board, which results in cost increases.
Meanwhile, further slimming down and higher functionality are desired in display panels for use in PCs and slim TVs and it is necessary to mount a larger number of electrical components in order to increase the scale of such display panels while pursuing the slimming down of such display panels. For this, the area and number of circuit boards must be increased, but at the same time there is a desire for a configuration that is capable of offering good heat radiation performance without increasing the thickness of a display panel, even though circuit boards are vertically arranged above and below.
In general, it is known that the heat radiation performance of electronic equipment degrades as the volume of the equipment decreases; however, pursuing the slimming down of display panels means reducing the device volume, which contradicts the desire for improved heat radiation performance.